JPS63117105A - Moisture removing device for blade cascade of steam turbine - Google Patents

Abstract

PURPOSE:To aim at improvement in efficiency of a blade cascade by providing a steam deflecting plate in an outer peripheral side interval between a stationary blade and a moving blade, and introducing steam into a steam passage again, wherein the steam is separated from moisture in the outer peripheral side interval. CONSTITUTION:A steam deflecting plate 6 is provided in an outer peripheral side interval 4 between a stationary blade 1 and a moving blade 3. A drain removing hole 5 is formed on the inner surface of the outer wall in the outer peripheral side interval. A radial turbine blade 7 is disposed on the front end of the moving blade so as to be connected with the outer peripheral side interval 4. Steam, which is introduced into the outer peripheral side interval 4, is separated from moisture, and thereafter, it runs through the radial turbine blade 7 so as to serve again. Therefore, the efficiency of a blade cascade can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is used in the technical field of efficiently separating moisture from steam generated in a steam turbine.

BACKGROUND OF THE INVENTION One of the losses that occur in the blade rows of steam turbines is moisture loss.

Moisture is generated when steam expands within the blade row and enters the wet area. Most of the moisture generated within the stator blades adheres to the ventral surface of the stator blades, collects together, and flows out from the outlet end of the stator blades as relatively large water droplets.

However, since the density difference between the steam and the water droplets is large, the water droplets reach the rotor blade inlet without being sufficiently accelerated. Since the velocity of the water droplet is small, at the inlet of the rotor blade, the water droplet collides with the back surface of the rotor blade 2 with a large relative velocity (see FIG. 3).

This results in moisture loss and reduces the efficiency of the blade row. In addition, since water droplets with high density collide with each other at a high relative velocity, the back surface of the rotor blade inlet undergoes erosion, shortening the life of the rotor blade and reducing reliability.To prevent a decrease in efficiency and reliability due to moisture. A piece of stellite, which has excellent lotion properties, is attached to the top.

However, when providing the drain removal groove 3 in the stationary blade 1,
Moisture attached to the ventral surface of the stator blade is removed, but moisture that does not adhere to the ventral surface of the stator vane and flows away with the steam flow cannot be removed (
(See Figure 3).

In order to improve this point, a space is provided at the outer periphery between the movable and stator blades as shown in Fig. 5, and the tangential (rotational direction) velocity component of the steam flow exiting the stator blades is used to create a space in this space. The steam is swirled inside, and the moisture that flows out along with the steam flow is separated by centrifugal force and discharged from the drain removal hole. A steam turbine blade cascade moisture removal device has been devised in which the moisture flows through the gap at the tip of the rotor blade and flows out downstream.

Problems to be Solved by the Invention In the steam turbine blade cascade moisture removal device illustrated in FIG. While more steam is led to the outer circumferential space between the rotor and stationary blades, from the perspective of the blade cascade, the steam that flows downstream through the seal gap at the tip of the rotor blades is leaked steam and does not do any work. If the amount is increased too much, the performance of the blade row will deteriorate.

Therefore, the performance improvement effect due to moisture removal in the mechanism illustrated in FIG. 5 cannot reach a very large value due to the balance with the performance deterioration due to an increase in leaked steam.

Means for Solving the Problems The present invention takes the following measures in order to solve the above-mentioned problems. That is, (1) an outer circumferential space between the stator blade and the moving blade into which water droplets flowing outward in the radial direction due to the steam flow flow; The steam is separated by a steam turning plate that flows in the radial direction and the swirling steam flow generated in the outer circumferential space between the moving and stationary blades, and water droplets in the steam adhering to the inner surface of the outer wall of the outer circumferential space are discharged from the outer circumferential space. It is equipped with a drain removal hole.

(2) The separated steam from which moisture has been removed by swirling in the outer circumferential space between the rotor and stationary blades passes through that area to do work, and is then guided to the downstream side by the radial turbine blade installed at the tip of the rotor blade. Be prepared.

According to the above-mentioned means, the steam that contains moisture that flows away without adhering to the ventral surface of the stator blades and is led to the outer circumferential space between the moving and stator blades is separated from the moisture by the centrifugal force caused by swirling. It does work through the part of the radial turbine blade installed at the tip of the rotor blade and flows away to the outlet of the rotor blade.

Embodiments Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an example of the blade row moisture removal device of the present invention.

Water droplets and stator blades that adhere to the ventral surface of the stator blade 1 and leave the outlet end 2
Water droplets that have passed through the stator blades 1 without adhering to the ventral surfaces of the stator blades 1 flow outward in the radial direction due to centrifugal force and steam flow, and flow into the outer peripheral space 4 between the stator blades 1 and the rotor blades 3.

Since the steam flow exiting the stationary blades 1 has a velocity distribution in the rotational direction, swirling occurs within the outer space 4 between the moving and stationary blades. This rotation produces a centrifugal separation effect, and water droplets in the steam adhere to the inner surface of the outer wall of the outer circumferential space 4 between moving and stationary blades, and are discharged through the drain hole 5.

The steam with low specific gravity flows toward the inner circumference again along the steam turning plate 6 provided on the inner circumference side of the outer circumferential side space 4 between the rotor and stationary blades, and passes through the radial turbine blade 7 provided at the tip of the rotor blade. Work and flow downstream.

FIG. 2 shows a portion of the radial turbine blade 7 provided at the tip of the rotor blade.

At the stationary blade outlet, the steam absolute velocity C is as shown in Figure 4.
Since s is sufficiently large, the steam relative velocity 1fs at the inlet of the rotor blade, which takes into account the circumferential speed U of the rotor blade 3, still has a component in the rotational direction. Therefore, the inlet portion of the rotor blade 2 is formed at an angle that matches this relative speed Ws.

On the other hand, the steam flow that has entered the outer circumferential space 4 between moving and stationary blades (FIG. 1) has an enlarged radius and a rotational velocity component that decreases due to attenuation associated with swirling.

The steam relative speed W, which takes into account the rotor blade circumferential speed U1 with respect to the speed CI, has no component in the rotational direction, and the steam flows into the radial turbine blade 7 in the radial direction.

The steam that has flowed into the radial turbine blade 7 in the radial direction is diverted in the axial direction along the steam passage formed by the radial turbine blade 7, and has a relative speed W having a rotational speed component, and then flows into the radial turbine blade 7 with a relative velocity W having a rotational speed component. 7 flows away.

This causes the steam to do work.

In addition, in the embodiment of the present invention described above, it may be used in combination with other moisture removal devices such as the drain removal groove 3 on the ventral surface of the stationary blade shown in FIG. 4, which is a conventional example.

Effects of the Invention According to the device of the present invention, the steam led to the outer peripheral space for moisture separation performs work through the radial turbine blade at the tip of the rotor blade after moisture separation, so that a lot of moisture rises. This increases the efficiency of the blade row without increasing steam loss.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part showing an example of a steam turbine blade row moisture removal device according to the present invention, FIG. 2a is a schematic view showing an example of a radial turbine blade provided at the tip of a rotor blade, and FIG. 2b is a schematic view showing an example of a radial turbine blade provided at the tip of a rotor blade. Its plan view, Fig. 3 is a diagram of the velocity relationship between steam and water droplets in the blade cascade, Fig. 4 is a sectional view showing a conventional stationary blade drain removal groove, and Fig. 5 is a conventional steam turbine cascade moisture removal device. It is a sectional view showing an example. 1. Stationary blade, 2. Outlet end, 3. Moving blade, 4. Outer space between moving and stationary blades, 5. Drain removal hole, 6 (and 1 other person) Figure 1 Figure 2α Figure zb Figure 5! 5.3-s"z'3 Procedural amendment (voluntary) December 9, 1985 Commissioner of the Patent Office Kuro 1) Akio Tono1, Indication of case Patent application No. 262821 of 19882,
Title of the invention Steam turbine blade row moisture removal device 3,
Person making the amendment Relationship to the case Name of patent applicant
Mitsubishi Heavy Industries, Ltd

Claims (1)

[Claims] 1. An outer circumferential space provided between a stator blade and a rotor blade, a steam turning plate provided within the outer circumferential space, and a steam deflection plate provided within the outer circumferential space between the rotor blades. A blade cascade moisture removal device for a steam turbine, comprising a drain removal hole for discharging water droplets in steam separated by a swirling steam flow and attached to an inner surface of an outer wall of the outer circumferential space from the outer circumferential space. 2. A radial turbine that receives steam from an outer peripheral space provided between a stationary blade and a rotor blade, a steam turning plate provided in the outer peripheral space, and the steam turning plate provided at the tip of the rotor blade. and a drain removal hole for discharging water droplets in the steam separated by the swirling steam flow generated in the outer space between the moving and stationary blades and adhering to the inner surface of the outer wall of the outer space from the outer space. Steam turbine blade cascade moisture removal device.